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Without a lengthy dissertation of why, I need to speed up the fan on my '63 Catalina. The present pulley is 7 3/4 inches two groove. The offset on the pulley is 1 3/4 from the water pump flange to the center of the first groove and 2 1/4 to the center of the second groove.  Has anyone done any legwork on this? I have checked with several aftermarket suppliers and no one I have talked with has an answer. Any help wold be greatly appreciated.

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Posted (edited)

In theory, you need to run a smaller pulley to speed up the water pump. So if you ran (say) a 20% smaller pulley, you'd need a 6 1/5 inch pulley on the water pump (based on your 7 3/4 pulley size). 

Having said that, at higher RPMs, if run your water pump too fast, you can run the risk of cavitation or not giving the coolant sufficient time in the radiator to cool down enough and you can cause overheating issues at the top end. I am not saying 20% isn't a good figure, I am talking beyond 20%.

An alternative might be an hi-flow electric water pump.

So it begs the question, what is the real problem are you trying to fix here?

There are under/over drive pulley systems out there commercially - mainly for the SBC/BBC/Ford engines. March may make one for Pontiacs but it may also require one of their kits too. It will require some research on the Internet to find one for the Pontiac V8 since I can't name one too readily off the top of my head.

Edited by Frosty

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The problem I am trying to fix is an overheat at slow speed. I presently have an approximately 6 inch crank pulley and a 7 3/4 inch water pump pulley. That is a pretty drastic underdrive. With the addition of A/C the problem surfaced, and before you ask I upgraded to a 4 row aluminum radiator and a 7 blade flex fan no clutch. I do not know for sure but it is entirely possible and considering the manufacturing time probable that the pump and fan speed was increased for air conditioned cars. In 100 degree weather it poses a problem. When the engine speed is increased from idle to about 1200 the engine temp starts to drop and a couple of miles at 60+ mph will drop the engine temp from 230 to 180 with A/C on. A 6" pulley would only put the water pump at crank speed which would not put it in any danger of cavitation. Obviously the cooling system is entirely capable of handling the heat load so the logical starting point is to change the underdrive on the water pump. If I am not mistaken it is the same 8 bolt water pump used on later engines that do not have the underdrive, and in some cases probably a slight overdrive.

The problem is that while there are pulley kits for Pontiacs out there they are all for post '65 engines and so far I have not found anyone that can tell me if the offset on the water pump pulley would be the same. I have e mailed several people without response. Therefore I am reaching out to the community to see if anyone has traveled this path already.

Interestingly enough Franks Pontiac parts does not know, i sent them the measurements of the pulley I need and they do not have anything in their stack that is the right size. I tried walking the entire yard at Pic a part only to find out that even the "old" stuff on their lot has serpentine belts. I do not think that I saw more than a dozen cars with v belts on them and nothing with a pulley even close to what I need.

The search continues.

 

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Spent alot of time searching the forum for this discussion we had about water pumps years ago, IndymanJoe  added  some great input on the plate inside the pump. (which was part of the overheat solution for me) but I can't seem to find it.

My 1st question for you Ol guy, is do you have a fan shroud??   2) what temp thermostat you running?  Have you tried any additives such as Water Wetter?

I understand your thinking on the pulley, but if that was the easy solution to a problem on a 55yr old car.  It would be in every book and shelf at any parts store. I had a heck of a time finding the correct Large water pump pulley for my 421 Tri Power.  NO other Pontiac water pump pulley that I tried worked, and I tried a bunch from different engines.  I ended up replacing everything in the coolant system, including 4 core rad, correct shroud, water pump, thermostat and hoses.  Now runs 180 until the temps reach the 90's + (usually in the middle of the Woodward Dream Cruise, stuck in traffic) then it climbs up around 210.

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Fan shroud, yes. I just spent a week redoing all of the radiator mounts and fan shroud. I have a 4 row aluminum radiator and a 7 blade solid hub (no clutch) fan blade. the problem is that I have a 6" crank pulley and a 7 3/4 inch pump pulley on a car that is geared so high that it is barely off idle on city streets. When the temp hit triple digits it started overheating as soon as the car quit moving, upward of 350 degrees. by putting it into neutral and bringing up the engine speed it would start cooling off, so to me that says lets speed up the fan. Less than two miles at freeway speed, 60 plus, will bring the temp down from 350 to 180 with the AC on so the problem is not cooling system capacity but air and possibly coolant flow. So considering how underdriven the water pump is in my mind it is the easiest starting point and the most logical.

I had a conversation with CFV racing and they have a great selection of pulleys I just need to find something with the correct dimentions and offset. I will post the results for anyone that might have the problem in the future.

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13 minutes ago, Old guy44 said:

Fan shroud, yes. I just spent a week redoing all of the radiator mounts and fan shroud. I have a 4 row aluminum radiator and a 7 blade solid hub (no clutch) fan blade. the problem is that I have a 6" crank pulley and a 7 3/4 inch pump pulley on a car that is geared so high that it is barely off idle on city streets. When the temp hit triple digits it started overheating as soon as the car quit moving, upward of 350 degrees. by putting it into neutral and bringing up the engine speed it would start cooling off, so to me that says lets speed up the fan. Less than two miles at freeway speed, 60 plus, will bring the temp down from 350 to 180 with the AC on so the problem is not cooling system capacity but air and possibly coolant flow. So considering how underdriven the water pump is in my mind it is the easiest starting point and the most logical.

I had a conversation with CFV racing and they have a great selection of pulleys I just need to find something with the correct dimentions and offset. I will post the results for anyone that might have the problem in the future.

It's a huge pulley on mine as well, probably the same as it's a 64 421.

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Food for thought....

On Lucy, she is a 462, still has the A/C compressor (A/C doesn't work -but  hey its a convertible), power steering pump, alternator. I run a stock thermo clutch fan and stock radiator shroud. Original 4-core radiator. I run a "wide mouth"/performance Mr. Gasket thermostat (180 degree if I recall properly). This 'stat' allows better water flow than the stock style thermostats. I have also installed an overflow/catch bottle from Speedway motors to allow any hot coolant to go into the catch bottle and get pulled back in later. No green stuff on the driveway neither.

Check your oil, is it low at all? At low idle for Lucy, low oil means more heat in the bearings that the cooling system has to compensate for.

Parade duty is good for Lucy. 4th of July, it was starting to creep up to 200. It was well over 90 degrees with high humidity that day. I had 7 people in a 5 passenger car too.

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If yours has an AC compressor it probably means that it was a factory air, unless it was an aftermarket. But an original 4 core radiator likely confirms that it was a factory air which means it had a heavy duty cooling system. Mine was not and everything has been upgraded to handle the addition of AC. This car was one of Pontiac's built under the influence cars. 10.25 compression with a two barrel carb and single exhaust. As I said built under the influence. If I had it to do over again I would have changed the pistons when I freshened up the engine and dropped the CR but it was low mileage and only had .004 taper on the front cylinders and .002 on the rest. Sooooo i just put in rings and bearings, I did replace the cam as a third of the lobes were well on the way to flat. Valley Head Service put in hard seats to make the heads unleaded friendly in short the engine is fresh and should be running  as efficiently as possible. I am convinced that the problem is that the water pump pulley is a FULL TWO INCHES BIGGER THAN THE CRANK PULLEY! My experience is that the 4 row aluminum radiators are great for cooling but are somewhat resistant to air flow. The engine is turning about 12-1400 rpm on the city streets, no tach but I have been listening to engines for over 60 years, and I am convinced that the fan is just not turning fast enough to provide adequate air flow. At idle with a 7 blade solid hub flex fan this thing will not move enough air to blow the hat off of your head. At 650 rpm idle the fan is probably only turning around  400 rpm.

I spent time on the phone with CVF racing and we came up with a fan pulley that is slightly smaller than the crank pulley with almost the correct offset, the groove spacing is about 1/8 different than the stock pulley which means that the front belt groove is about .070 too far forward and the rear groove is about .070 too far back.  I have seen cars come from the factory with more misalignment than that. It is for some model of AMC. When it comes I will put it on and will follow up with the results. Assuming that it works as planned I will list the pulley number.

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OK finally got the pulley from CVF racing. It is an AMCL2WP. Fits some model(s) of AMC and Jeep. It is almost a perfect backset and belt spacing. I just had to whack out a .060 spacer from some heavy gauge sheet metal in the garage and do a small amount of grinding on the water pump ribs but it seems to be working fine. The pulley is just over 6 inches in diameter and along with everything else done the engine temp has not seen the high side of 190.

I was going to give it the ultimate test today going downtown in the gruesome LA traffic as the temps around here are back in triple digits but with every gremlin I have chased in the A/C system the one thing I have not had is a leak. Along with all the other things done I replaced the A/C condenser to hopefully bring the nozzle temp down. I drove it yesterday and noticed that while with the additional air movement the engine was doing great  the A/C nozzle was climbing back up to 60 degrees. I parked it in the garage and when I got the time  I went out to put the gauges on it to see what was going on. I screwed the gauges on and it was registering 10 pounds pressure. I looked around and there is oil residue around the outlet hose on the condenser. I disconnected the hose and the o ring looks fine so did I get a bad condenser? I pissed off the A/C gods about 8 months ago and they are not letting up. I am getting ready to leave town Wed. AM so will not have time to check it until I get back.

The A/C problem is for another forum but with regards to the engine temp the smaller pulley seems to be the last piece of the puzzle.

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Let us know what happens.

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OK back in town and I have put a few miles on it since replacing the pulley. I am still trying to work the gremlins out of the A/C but that is fodder for another forum. With regards to the engine temp the aftermarket temp gauge I temporarily installed under the dash seems to hold steady around 190 in 95+ degree ambient temp with the A/C on high constantly. It will climb up to 200 in stop and go freeway traffic where you are sucking in all the hot air created by the other 12 million cars on the Los Angeles freeway system but speeding up the fan seems to have corrected the overheat. This is one of the cars that does not have a temp gauge but has the hot and cold idiot lights, as memory serves the hot light comes on at 245 degrees so 200 is entirely acceptable.

I do not remember if I mentioned it but to install the pulley I needed to do a little grinding on the water pump which i accomplished with a 4" hand grinder without removing the pump and the bolt holes need to be slotted a little bigger. The AMC pump has about a 1/4 inch smaller bolt circle.

I hope that this information may help someone else with a similar problem as it represents a lot of hours finding the pulley.

P.S. the A/C problem was a loose fitting on the inlet of the condenser. Forgot to tighten it!  

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